<body>
<div style="width: 500px; height: 500px; background: blue">
  This is an extremely contentful div. I swear.
</div>
<script>
const run_test = async () => {
  await new Promise((resolve, reject) => {
    new PerformanceObserver(list => {
      const entries = list.getEntries();
      for (let entry of entries) {
        if (!entry.url) {
          // Once we have an LCP entry for the div, we add the image and wait
          // a bit.
          const anim = new Image();
          anim.src = "/images/anim-gr.png";
          document.body.appendChild(anim);
          setTimeout(resolve, 100);
        } else if (entry.url.includes("anim-gr.png")) {
          // We should never get an entry for the image.
          reject("The image should not be an LCP candidate.");
        }
      }
    }).observe({type: "largest-contentful-paint", buffered: true});
  });
};
</script>


